Combination heat exchanger and reservoir for various media liquids or gases



5 A. LA v. LAWBAUGH 2,572,735

CO'IBINATION HEAT EXCHANGER AND RESERVOIR FOR VARIOUS MEDIA LIQUIDS 0R GASES Filed Feb. 8, 1949 3 Sheets-Sheet 1 uwenIor 2.0 x Fig.5. New

' rney Oct. 23, 1951 A. LA v. LAWBAUGH 2,572,736

COMBINATION HEAT sxcmmcsn AND RESERVOIR FOR VARIOUS MEDIA LIQUIDS OR GASES 3 Sheets-Sheet 2 Filed Feb. 8, 1949 A. LaVZeUe Lowbaugh fvwez don by W A mgy Oct. 23, 1951 A. LA v. LAWBAUGH 2,572,735

CQHBIQATION HEAT EXCHANGER AND RESERVOIR FOR VARIOUS "EDIA LIQUIDS 0R GASES Filed Feb. 8, 1949 3 Sheets-Sheet 3 I AUDI-may Patented Oct. 23, 1951 UNITED' STATES PATENT 1 2,572,736 GFFICE I CODIBINATION HEAT EXCHANGER AND RESERVOIR FOR LIQUIDS OR GASES VARIOUS MEDIA 6 Claims.

This invention relates to a combination heatexchanger and reservoir for various media, liquid or gas.

More specifically speaking the invention relates to means for cooling oil which is circulated through an internal combustion engine for the purpose of lubricating the moving parts associated with an engine.

' Oil cooling systems now on the market, used in conjunction with the internal combustion engines of airplanes, are needlessly heavy and complex, and unnecessarily expensive to manufacture. Because of considerableoil being consumed during prolonged flights as the result'of a breaking down of the chemical equilibrium of the oil a reservoir must be provided sufficiently large to store the amount of oil thus broken down; this reservoir being connected to the engine and through the engine breather to the atmosphere.

To such conventional structure it is also common practice to add an air cooler wherein air conducts the heat from the oil, which cooler in certain cases is quite heavy and relatively expensive owing to copper, nickel or brass being used in its construction; and inother cases though reasonably light is very expensive owing to aluminum being employed, a metal which is not only very costly but which must be fabricated and assembled at a high cost and under exacting conditions.

Furthermore, in the aforesaid conventional constructions the oil cooler must be so constructed as to withstand a pressure of one hundred pounds per square inch, which means that even quite heavy tubing will not meet requirements without distortion, necessitating the building in'of a heavy, double-walled by-pass jacket around the tube bundle, the flow through such jacket being directed by a heavy, complicated valve, which, when an excessive fluid pressure occurs, diverts the oil from its normal path between theclosely spaced cooling tubes, so as to prevent damage. This valve is either of the pressure relief type or the thermostatic control type,both of these types utilizing a valve structure and operating means therefor which add materially to original and maintenance cost.

My invention overcomes the foregoing 'objectionable features in an exceedingly simple and effective manner by providing a device which, in a single simple unit combines the functions of oil cooler and oil reservoir and in which gravity flow of the oil is substituted for pressure flow thereof through the bundle of air cooled tubes, my device being operative at a fluid pressure of not more than five pounds per square inch.

Furthermore, it is an object of the invention to provide, in a heat-exchanger for lubricating 011, an oil conducting system wherein the tend ency to develop leaks is eliminated, notwithstanding the thin-walled conduit used.

Another object is to eliminate the tendency to 2 leakage which is has been hitherto necessary to rtsontend with in pressure flow oil cooling strucures.

Also an important object is to provide an oil cooling system operable under very low' fluid pressures-per square inch.

Still another object is to provide an oil cooling device which, when applied'to an aircraft's engine, will maintain, during cold weather, a more uniform temperature of the oil in the reservoir provided therefor, thus safeguarding against the oil congealing; and conversely, in hot weather to provide for the maintenance of a lower temperature for the oil in the reservoir.

This'in a continuation-in-part of my application for patent filed March 16, 1946, Serial No. 654,987, now abandoned.

Other objects, advantages and features of invention will hereinafter appear.

Referring to the accompanying drawings, which illustrate a preferred embodiment, of the inventiou, I

Fig. l is a plan view of the device, fragments being shown of the meansfor the connection thereof with an internal combustion engine.

Fig. 2 is a front side elevation of the structure shown in Fig. 1.

Fig. 3 is a vertical section taken on line '3--3 of Fig. l.

Fig. 4 is'a perspective view of the device, oil reservoir omitted.

Fig. 5 is an elevation thereof looking at the right end of Fig. 2.

Fig. 6 is a cross section on line 6--6 of Fig. 1.

Fig. 7 is an enlarged view of the device in perspective with portions-of the casing broken away in order to disclose interior structure.

Fig. 8 is a plan view showing the device as applied to aircraft.

Fig. 9 is a side elevation of the structure show in Fig. 8.

Fig. 10 is an elevation showing separately the air cooler as viewed in Fig. 9. p I

Fig. 11 is an elevational view of a portion of the complex system upon which my invention is by means of couplings 24, and arepan shaped.

Within the tank baliiing S extends adjacent to r all sides of said assembly of tubes except beheath. thmQs'aid baflling cooperating with head-.

ers partially to encase said assemblypf tubes,

there being above and'on each" side of the baflling a space between it and the wall of the tank. Said bailling has at each side a vertical portion or apron which terminates along its lower edge in an outwardly directed reinforcing flange 25, welded to the tube assembly 4.

An oil supply pipe made up of sections 2 and 8 leads horizontally from the engine and. then downwardly, through the top wall of the tank with a fluid tight fit, and thence passes downwardly through the underlying space and through an opening 9 in the upper part of the baflling 5. Said opening 9 is of a considerably greater diameter than the pipe which passes through it, thus providing an annular space for backflow of the oil in an upward direction. The open lower end of the pipe is below the opening 9 and slightly above the underlying assembly of tubes 4. Said annular space afforded by the opening 9 is the preferred, but obviously not the only possible passage means for affording a by-pass through which a portion of the oil can escape at times upwardly through the upper side of the partial housing formed by the aforesaid baffling.

From the lower side of the tank I an oil outflow conduit III, connected with the tank in a fluidtight manner by a fitting 28, conducts the cooled oil to the engine.

The tank I is provided with a capped infill pipe 29 and with anoverflow and vapor tube Ia which is vented through the engine and thence to atmosphere by means of the engine breather whereby to operate the coolin tank at a pressure of not more than five pounds per square inch. The applicant is aware that some patents show a similar pipe as a part of the oil radiator, and in some cases connecting with the engine. But in the case of automobiles and similar installations, such a connection does not provide a vent to atmosphere without a considerable pressure drop. For automobile engines it is not uncommon to operate at crank-case pressures of 7-12 pounds per square inch and in the case of older cars, clogging of passageways and the inadequate breathers result in even higher operating pressures. Such high crank case pressures are the cause of high rate oil blow-by at the rings which is commonly termed oil burning." The applicant's invention is specifically designed to operate at pressures not to exceed 5 pounds per square inch. The over-flow and vapor tube la, is normally one-half inch in diameter connectable to the engine I 4. The pressure drop in such a line is negligible and the much larger oil passages in the engine provide little pressure drop. Finally, the breather is so designed as to remove most of the solid oil by impingement and gravity, permitting the excess pressures to vent over-board to atmosphere with considerably under 5 pounds per square inch pressure drop.

In Figs. 8, 9 and 10 the device is shown associated with an aircraft comprising a fuselage II, wings I2 and nacelle I9. In these three views the various parts ofthe devic are lettered in the same manner as in the preceding views. The cooling tank I is installable in different positions. It may be installed directly on thesair baille of a reciprocating engine installation.

Figs. 10 and 11 show a direct comparison between my simple device and the complex conventional system. Moreover my device is assembled liquid tight for efficient operation under not more than five pounds per square inch pressure.

The parts shown in Figs. 8, 9 and 10 may be 'joined by brazing, or other suitable means.

Among objectionable parts shown in Fig. 11,

eration a sumcient quantity of oil is introduced through the filling pipe 28 to bring the oil level up to the level indicated at I, said filling pipe being positioned sufliciently low to insure that considerable air space always remains above the oil. This airspace amounts to approximately ten per cent of the contents of the oil tank I and is provided to accommodate extraordinary conditions of oil flow and foaming and to prevent harmful surges of oil within the system. When the apparatus is put into operation hot oil from the engine enters the conduit 2, courses down into the tank I, and after gravitating into the space enclosed by the baiiling 5 passes down through the interstices between the air cooled tubes 4, after which it flows out through suction conduit III. The suction coming from the conduit It! creates a negative pressure area subjacent to the assembly of tubes 4 thus facilitating the gravity impelled flow of oil downwardly between the tubes. Under certain operating conditions, solid oil may be returned to the engine through the over-flow and vapor tube Ia simultaneously with the return flow through the suction conduit III. This is a unique and advantageous operation in theiapplicants cooling tank invention.

Ram air passes through the tubes 4 impelled by the forward motion of the aircraft or other vehicle on which the device is mounted, or in other instances may be mechanically driven through the tubes, in any case an efllcient heat exchange resulting from the air assir'nilating heat from the surrounding oil through the thin walls of the tubes.

In case the oil attains so much viscosity as to interfere with its normal flow between the cooling tubes, it will fill the space 21 between the assembly of tubes and the top portion of the battle 5. Such a layer of hot oil usually has a sufliciently high temperature to alter the viscosity of the oil underlying it, so that the normal oil flow is again resumed. But if the congealed condition of the oil continues the incoming hot oil will pass up outthrough the annular by-pass passage 9 to mingle with the oil stored in the tank I, whence it will again pass through the outflow conduit I0 or simultaneously return to the engine through the over-fiow and vapor tube Ia.

Describing in further detail the combination of my improved oil cooling means with aircraft,

as illustrated in Figs. 8, 9 and 10, the engine oil pump I5 (see Figs. 8 and 9) withdraws the cooled oil through pipe In from the tank I and conducts the warmed oil back to said tank through the supply pipe 2. This structure is a marked simplification over the conventional arrangement shown in Fig. 11, for it eliminates the pipe I 9 of the latter view, and also eliminates the cooling tank 20 considered as a structure located outside of the oil cooler, designated I8 in the former view. Hence with the device installed as shown in Figs. 8 and 9, it will be obvious that the ram air entering the duct l6 passes through the open tubes 4 Y of the tube assembly which is surrounded by the hot oil, onto the rear duct I1 preparatory to its exit from the device. Durin the operation of the apparatus the pipe la serves as an over-flow and vapor tube for the reservoir l which communicates with the engine [4.

Describing additional structural details, the horizontal top portion of the baflling has at each end a downwardly directed angular flange 5a the lower part of which extends outwardly and is welded or otherwise secured to the header 3 at that side of the oil tank. Said flanges 5a are of suflicient vertical extent to maintain the horizontal run of the baiiling sufliciently spaced above the tube assembly 4, to provide the oil space 21. It is desirable in some instances to provide a vertical passageway in that vertical portion of the baflle 5 on either side of the tubes. This vertical passageway would connect with the space 21 above the tubes and below the horizontal run of the bafiie 5 and discharge at the flange 25, at the bottom of the vertical run of the baiiie 5. Such an additional by-pass may be used for certain phases of cold weather operation but is obviously not the only means of so doing.

In Figs. 8 to 11 the air entrance and exit ducts l6 and H are shown, and also the engine 14.

I claim:

1. In a structure of the kind described, a cooling tank enclosed on all sides, an assembly of parallel slightly spaced apart air conduit tubes extending through said tank, bafliing inside of said tank having a horizontal portion in an adjacent relation to the top of said tube assembly,

and vertical portions adjacent to opposite sides thereof, said vertical portions of the baffling being inwardly spaced from the opposed tank walls, headers at opposite sides of the tank having a fluid tight fit around the individual tubes of said assembly of tubes, there being an opening in an upper portion of said bailling downwardly spaced from a top portion of the wall of the tank, and in an upwardly spaced relation to said tube assembly, and an oil supply conduit passing with a liquid tight fit through the top wall of the tank and thence downwardly through said openin to supply the oil from an engine to the interspaces of said assembly of tubes, there being a clearance around said conduit between it and the edge of said opening through which it passes, and an oil outflow conduit leading from the lower side of said tank to conduct the cooled oil back to said engine.

2. In a structure of the kind described, a cooling tank enclosed on all sides, an assembly of parallel slightly spaced apart air conduit tubes extending through said tank, bafliing inside of said tank having a horizontal portion in an adjacent relation to the top of said tube assembly and vertical portions adjacent to opposite sides thereof, said vertical portions of the baffling being inwardly spaced from the opposed tank walls, headers at opposite sides of the tank having a fluid tight flt around the individual tubes of said assembly of tubes; there being a vertical space between said horizontal portion of said baflling and the top wall portion of said tank, an oil supply conduit to conduct the oil from an engine, said conduit passing downwardly through the top wall portion of said tank with a liquid tight flt and thence through the horizontal portion of said batiling underlying said space, and an oil outflow conduit leading from the lower side of said tank to conduct the cooled oil back to said engine, there being backfiow passage means for the 011 leading upwardly through said baffling from the space occupied by said assembly of tubes.

3. The subject matter of claim 2, and there being a space between the lower side of said assembly of tubes and the lower wall of said tank, said oil outflow communicating with said space.

4. In a. structure of the kind described, an oil cooling tank enclosed on all sides, an assembly of air conducting oil cooling spaced apart tubes supported by and bridging the space between opposite walls of said tank, there being an oil containing space within said tank parallelin the sides of said assembly of tubes, a horizontally disposed baille plate portion mounted subjacent to the upper wall portion of said tank and superjacent to said tube assembly, an oil supply conduit leading downwardly through the top wall of the tank and thence through said baiile plate portion to conduct lubricating oil from an engine to the space between said baflle plate portion and said tube assembly, there being oil backfiow passage means to by-pass oil upwardly through said baille plate portion, and an outflow conduit positioned to conduct the cooled oil from the space below said tube assembly to said engine.

5. The subject matter of claim 4, and said oil cooling tank enclosed on all sides including headers into which the tubes of said assembly extend at opposite sides of the tank, and said horizontal baiii plate portion having at each of opposite sides a downwardly directed flange, said flanges resting upon said headers and servin to support said baiile plate portion superjacent to said tube assembly.

6. In a structure of the kind described, a cooling tank enclosed on all sides, an assembly of slightly spaced apart tubes extending through said tank, pan-shaped headers having bottom portions forming wall portions of the tank, said bottom portions having through them a multiplicity of adjacent openings fitted around the individual tubes of said assembly in a liquid tight manner, the flange portions of said pan-shaped headers projecting outwardly from the tank for connection with air ducts, said assembly of tubes being spaced downwardly from the upper side of v the tank thus providing an oil-containing space above the tubes, a baflle including a horizontal portion carrying downwardly directed side flanges each of which is secured at its lower edge to the header at its side of the tank thus supporting said bailling portion in a spaced relation both to the top wall of the tank and to said assembly of tubes, an oil supply conduit leading from an engine downwardly through both the top wall of the tank and said horizontal bafiling portion and discharging between the baiiling and the uppermost of the tubes of said assembly, and conduit means for conducting the cooled oil back to said engine from said tank.

ALBERT LA VIELLE LAWBAUGH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,101,969 Still June 30, 1914 1,617,433 Beisel Feb. 15, 1927 1,717,716 MacKintosh June 18, 1929 1,776,726 Gross Sept. 23, 1930 1,870,809 Handy Aug. 9, 1932 2,298,996 Woods Oct. 13, 1942 

